This application seeks to deepen our understanding of the complex psychological and physiological processes that underlie the production of human speech. Using the SLIP task, a speech error eliciting technique, we will investigate why previous research has led to conflicting findings. In particular, we will discriminate between feed-forward and interactive models of speech. Additionally, the role of articulation in speech errors will be investigated, extending the models to account for post-planning influences on speech production. This will be accomplished by recording articulation errors using electropalatography (EPG), electromagnetic articulography (EMA), and ultrasound techniques during the SLIP task. Lastly, we will extend the scope of the psychological and physiological evidence from the SLIP task to a more natural task, the Network task which allows participants to produce connected, purposeful speech under experimental control. This project will make a substantial contribution to our understanding of the interplay between mental and physical process of speech and develop a unified approach to articulatory analysis across a number of techniques, including EPG, EMA, and ultrasound.